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United States Patent |
5,011,274
|
Wagner
|
April 30, 1991
|
Eyeglass frame comprising a screw joint which is protected from becoming
loose
Abstract
This invention relates to an eyeglass frame comprising members,
particularly hinge members, which are connected by a screw joint which is
protected from becoming loose. The screw joint comprises a single metal
part, which consists of a screw, which does not tend to become seized and
to become clamped in the relatively movable hinge eyes. Because plastic
parts are not required in the joint, the screw may remain installed during
soldering work. This is accomplished in that the screw has a conical head
portion which tapers with an included angle of 20 to 40 degrees,
preferably 30.degree., and when the screw has been screwed into the frame
the head of the screw extends in a conical opening in a member of the
frame and in said opening defines with said frame member a clearance angle
of 1 to 3 degrees and a clearance space axially adjoining the head. In
such a joint the screw can firmly be tightened so that the high friction
will prevent the screw from becoming loose spontaneously. On the other
hand, the application of an excessive pressure per unit of area to the
hinge eyelets will be avoided.
Inventors:
|
Wagner; Reiner (Ispringen, DE)
|
Assignee:
|
OBE-Werk Ohnmacht & Baumgartner GmbH & Co. KG (Ispringen, DE)
|
Appl. No.:
|
439289 |
Filed:
|
November 20, 1989 |
Foreign Application Priority Data
| Apr 17, 1989[DE] | 8904802[U] |
Current U.S. Class: |
351/121; 351/90; 351/153 |
Intern'l Class: |
G02C 005/14; G02C 005/22; G02C 001/08 |
Field of Search: |
351/141,153,121,90-102
411/6,168,169,399,955,960
16/228
|
References Cited
U.S. Patent Documents
2833325 | Feb., 1954 | Laisy | 411/960.
|
3427681 | Feb., 1969 | Smith, Jr. | 351/141.
|
Primary Examiner: Bovernick; Rodney B.
Attorney, Agent or Firm: Dvorak and Traub
Claims
I claim:
1. In an eyeglass frame comprising
at least two frame members, one of which is formed on opposite sides with a
tapped bore and with a conical opening, which tapped bore and conical
opening are axially aligned and open toward each other, and
a screw having a screw-threaded shank, which is screwed into said tapped
bore, and a conical head portion, which tapers toward said shank and
extends into said conical opening and engages said one frame member in
said conical opening,
the improvement residing in that
said conical head portion tapers with an included angle of 20 to 40 degrees
and defines with said one frame member in said conical opening a clearance
angle of 1 to 3 degrees and a clearance space which surrounds said shank.
2. The improvement set forth in claim 1, wherein said conical head portion
tapers with an included angle of 30.degree..
3. The improvement set forth in claim 1, in which said at least two frame
members constitute hinge members.
4. The improvement set forth in claim 3, wherein
said one frame member comprises axially spaced apart two outer hinge
eyelets, which are formed with said tapped bore and with said conical
opening, respectively,
an additional frame member consists of an intermediate hinge eyelet, which
extends between said two outer hinge eyelets and is formed with an
untapped opening, which communicates with said conical opening and with
said tapped bore, and
said shank extends through said untapped opening in said intermediate hinge
eyelet into said tapped bore.
5. The improvement set forth in claim 4 as applied to an eye-glass frame
comprising a rim and two bows, each of which is hinged to said rim by one
of said hinges, wherein
said intermediate hinge eyelet of each of said hinges is connected to said
rim and said outer hinge eyelets of each of said hinges are connected to
one of said bows.
6. The improvement set forth in claim 4, wherein
said tapped bore has an untapped portion, which communicates with said
untapped opening in said intermediate hinge eyelet and
said untapped opening in said intermediate hinge eyelet communicates with
said clearance space.
7. The improvement set forth in claim 1, wherein said conical head portion
occupies one-half to two-thirds of the volume of said conical opening in
said one frame member.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an eyeglass frame comprising members,
particularly hinge members, which are connected by a screw joint which is
protected from becoming loose.
2. Description of the Prior Art
It is known that this object can be accomplished by plastic elements which
control the friction between the parts of the joint. Such means consisting
of plastic have been disclosed, e.g., in German patent specification No.
23 56 818 but must be removed when soldering work is to be performed on
the eyeglass frame and must subsequently be inserted again. Screws
provided with restraining means which consist entirely of metal have
already been used and have been described, e.g., in German Utility Model
86 26 588 and Austrian patent specification No. 386,486. But such
restraining means are provided with nuts, so that they are bipartite and
in accordance with the last-mentioned reference said restraining means
comprise a conical member, which is inserted into mating eyelets of the
hinge so that inaccurate fits may result in a clamping of the hinge. From
German patent specification No. 89 49 18 it is known in small hinges to
provide a conical screw head which fits a conical opening in a member of
the frame. In that case the resulting joint can be intentionally loosened
only with difficulty, particularly if the screw has been firmly tightened,
and such tightening and loosening will usually damage the head of the
screw adjacent to the groove so that the screw cannot be re-used.
SUMMARY OF THE INVENTION
It is an object of the invention to provide such restraining means which
consist only of a metal screw and which will not become seized and will
not be clamped in the relatively movable hinge eyelets and which does not
require the use of plastic material so that it may remain installed when
soldering is to be performed.
In an eyeglass frame comprising members, particularly hinge members, which
are connected by a screw joint, which is protected from becoming loose,
that object is accomplished in accordance with the invention that the head
of the screw is conical and has an included angle of 20 to 40 degrees,
particularly of 30 degrees, and is adapted to be screwed into one member
of the frame so that the head of said screw extends in a conical opening
of said one member of the frame, which conical opening has such a taper
that a clearance angle of 1 to 3 degrees is defined in said conical
opening between said conical head and said one frame member. In that case
a strong tightening of the screw will result in a friction which is so
high that a spontaneous loosening of the screw will be prevented and an
excessively high pressure applied per unit of area of the hinge eyelets
will also be avoided. The hinge will easily be operable but the screw
joint will be protected from becoming loose. In such a joint the tensile
load on the screw threads will be low and the pressure per unit of area
applied to the sliding surfaces of the hinge owing to the axial tightening
of the screw will be low and will uniformly be distributed. Owing to the
clearance angle between the conical head and the conical opening the
forces exerted in the outer portion of the conical opening will be much
stronger than in the inner portion so that a compressive stress will arise
in the outer portion and will result in a favorable distribution of the
forces exerted on the sliding surfaces of the hinge.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side elevation showing a new eyeglass frame.
FIG. 2 is a transverse sectional view showing the frame of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Details of an eyeglass frame provided in accordance with the invention with
a screw joint which is protected from becoming loose are apparent from the
drawing, which illustrates a preferred embodiment, which will now be
described.
The eyeglass hinge shown in the drawing consists of three frame members,
namely, of the two outer hinge eyelets 1 and 2, which may constitute
bow-side or rim-side hinge members, and an intermediate hinge eyelet 3,
which may constitute a rim-side or bow-side hinge member.
The hinge-screw comprises a screw-threaded shank 4 and a conical head
portion 5, which tapers toward the shank 4 with an included angle between
20 and 40 degrees, in the present case with a preferred angle of 30
degrees. That head portion 5 extends in a conical opening 6, which tapers
in the same direction and defines with the conical head portion 5 of the
screw a clearance angle of 1 to 3 degrees.
In the embodiment shown by way of example the conical opening 6 is formed
in an outer hinge eyelet 1 and the head portion 5 extending in the opening
6 defines in said opening 6 with the hinge eyelet 1 a clearance space 7
around the shank 4.
The other outer hinge eyelet 2 is formed with a tapped bore 8.
The shank 4 can be inserted through the conical opening 6 of the outer
hinge eyelet 1 and through an untapped bore 9 in the intermediate hinge
eyelet 3, which is disposed between the outer hinge eyelets 1 and 2, into
the tapped bore 8 and can be screwed into the latter until the conical
head portion 5 at its top engages the outer hinge eyelet 1 in the conical
opening 6. The conical head portion 5 occupies one-half to two-thirds of
the volume of the conical opening 6, as best viewed in FIG. 2. In that
position the untapped bore 9 communicates with the clearance space 7 and
with an untapped portion of the tapped bore 8.
The arrangement which has been described and shown permits a firm
tightening of the screw so that the high friction between conical surfaces
will prevent the screw from spontaneously becoming loose whereas the
application of an excessive pressure per unit of area of the hinge eyelets
will be avoided.
The screw having a conical head which is illustrated here may be used not
only in three-part eye-glass hinges but may also be used in five-part
eyeglass hinges. Advantages will generally be afforded by the use of the
screw joint in eyeglass frames comprising a screw joint which is to be
protected from becoming loose, for instance, in connection with closing
blocks.
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